TEHRAN — Two years ago, Iranian activists used social media sites as engines to organize massive anti-government demonstrations. But now, activists say, the limitless freedoms available online are proving to be a distraction from real-world dissent.

Instead of marching in the streets, the same doctors, artists and students who led the demonstrations in 2009 are playing Internet games such as FarmVille, peeking at remarkably candid photographs posted online by friends and confining their political debates to social media sites such as Facebook, where dissent has proved less risky.

"Tehran Persian Nights" - Online, Iranians now brazenly show the parts of their lives that they used to keep secret from the state and others. Pictures of illegal underground parties, platinum blond girls without headscarves and couples frolicking on the holiday beaches of Turkey, are all over Iranian social media.

“We have become couch rebels, avoiding the dangers that real changes bring,” said a 39-old Iranian artist who spends most days juggling between two laptops and 1,300 online friends. “Our world online is like an endless party with no rules, and that keeps us very busy.”

The artist insisted that she be identified only by her first name, Jinoos, to avoid government retaliation. She said she had attended a demonstration in February but, on returning home, found that all of her friends had remained online, posting news about the protest from the safety of their homes.

More than anything else, the relative quiet on the streets of Tehran can be explained by the ferocity of the government crackdown that followed the protests of 2009. Dozens of protesters were killed, hundreds were arrested, and many were sentenced to long prison terms; since then, critics of the government have preferred to vent their anger in private.

But many Iranians also acknowledge that they increasingly have been drawn into virtual worlds, which serve as outlets for self-expression in forms otherwise unimaginable in a country where a boy and a girl walking hand in hand along a boulevard could be arrested on charges of improper relations.